Supply Chain Performance Improvement: The Role of IT Presented By: Bibhushan Entry No: 2002RME027 Supervisors: Prof. S. Wadhwa and Prof. Anoop Chawla
Presentation Outline
Research Context and Motivation
Research Objectives
An Overview of the Research Work
Significant Contributions of Research Work
Publications
Response to Examiner’s Comments
Research Context and Motivation
Simulation for Supply Chain Modeling and Analysis
Used for analysis of complex systems
Type of problems modeled range from tactical to strategic
Object-Oriented Simulation Modeling
Detailed model of a complex system can be made by combining basic building blocks
Has advantages of inheritance, encapsulation, modularity, etc.
Multiple Entity Flow Perspective
Five flows: Material, Information, Money, Resource, Decision
Focus on Inventory Management to improve IT facilitated SC performance
Research Objectives
Highlight the research motivation to
Develop an object-oriented supply chain simulation-modeling environment
Develop demonstrative models to illustrate the efficacy of the approach in SC performance
Study the inventory management in supply chains working under stochastic demands
Research Objectives
Develop an object-oriented supply chain modeling and simulation environment based on multiple-entity flow perspective which should be capable of:
Modeling the flow of multiple entities
Stochastic modeling
Adding user-defined decision rules in addition to major control decision rules
User-friendly and cost effective
Robust modeling by means of effective error handling and fool-proofing in data input
Distributed simulation
Research Objectives
Analyze inventory management along multiple criteria (demand variance, inventory, service level etc.)
Understand the effect of Expected Service Quality (ESQ) on different inventory policies
Determine optimal ESQ for each node
Determine optimal Information sharing level for the ESQ levels found above
Understand the effect of ordering and capacity constraints on different inventory policies
Determine Optimal Ordering and Capacity constraints for each node
Determine the optimal information sharing level for ordering and capacity constraint levels determined above
Determine the effect of change in Coefficient of Variance (COV) on each supply chain node
Determine the optimal Information sharing level for different COV levels
Overview of Research Work
Organization of Thesis
Conceptual Framework
Simulation Modeling Environment
Performance of Supply Chain under Controlled Variability
Optimizing ESQ for Supply Chain Nodes
Optimizing Optimal Ordering and Capacity Constraint levels for Each Supply Chain Node
Understand the Effect of Changing COV on supply chain
Organization of Thesis
Conceptual Framework
A Generic Model of Supply Chain
Object Oriented Modeling Perspective
Modeling of Elementary Supply Chain Constructs
Hierarchy of Object Used in Supply Chain Modeling
Modeling Supply Chain Decisions
Simulation Modeling Environment
Modeling the Supply Chain Building Blocks
Modeling the manufacturing system
Modeling the transports
Modeling the Player Role
Modeling the Supply Chain Node
Modeling the Inter-Node Interactions
Defining Inter-Node Relationships
Defining Inter-Node Lead Times
Defining Inter-Node Speeds
Defining Inter-Node Distances
Defining Product Demands
Simulation Modeling Environment
Modeling Supply Chain Decisions
Source Selection Policies
Inventory Control Decisions
Transportation Decisions
Production Planning Decisions
Performance Metrics
Inventory Related
Demand Related
Service Related
Supply Chain Model for Research
Model Verification and Validation
Performance of Supply Chain under Controlled Variability
Experimental Setup
Demand impulses
Simulation parameters
Balancing the inventory policies
Performance metrics considered
Effect of Transformed Relative Impulse Amplitude (TRIA) on the Supply Chain
Effect of TRIA on the Supply Chain using Demand Flow Policy (DFP)
Effect of TRIA on the Supply Chain using Order Q Policy (OQP)
Effect of TRIA on the Supply Chain using (s, S) Policy (sSP)
Effect of TRIA on the Supply Chain using (s, Q) Policy (sQP)
Performance of Supply Chain under Controlled Variability
Effect of Balance Gap (BG) on the Supply Chain
Effect of BG on the Supply Chain using DFP
Effect of Negative Impulse BG (NIBG)
Effect of Positive Impulse BG (PIBG)
Effect of BG on the Supply Chain using OQP
Effect of NIBG
Effect of PIBG
Effect of BG on the Supply Chain using sSP
Effect of NIBG
Effect of PIBG
Effect of BG on the Supply Chain using sQP
Effect of NIBG
Effect of PIBG
Performance of Supply Chain under Controlled Variability
Effect of Number of Impulses (NI) on the Supply Chain
Effect of NI on the Supply Chain using DFP
Effect of Number of Negative Impulses (NNI)
Effect of Number of Positive Impulses (NPI)
Effect of NI on the Supply Chain using DFP
Effect of NNI
Effect of NPI
Effect of NI on the Supply Chain using DFP
Effect of NNI
Effect of NPI
Effect of NI on the Supply Chain using DFP
Effect of NNI
Effect of NPI
Performance of Supply Chain under Controlled Variability
Effect of Impulse Width (IW) on the Supply Chain
Effect of IW on the Supply Chain using DFP
Effect of Negative Impulse Width (NIW)
Effect of Positive Impulse Width (PIW)
Effect of IW on the Supply Chain using DFP
Effect of NIW
Effect of PIW
Effect of IW on the Supply Chain using DFP
Effect of NIW
Effect of PIW
Effect of IW on the Supply Chain using DFP
Effect of NIW
Effect of PIW
Supply Chain Processes
Plan
Balances aggregate demand and supply
Source
Procures goods and services to meet planned or actual demand
Make
Transforms product to a finished state
Deliver
Provides finished goods and services
Return
Post-delivery customer support
A Generic Model of Supply Chain
Supply Chain Flows
Primary Flows (Between Nodes)
Material Flow
Information Flow
Cash Flow
Secondary Flows (Only inside Node)
Resource Flow
Decision Flow
Object Oriented Supply Chain Simulation
Simulation is a technique where computers imitate the operations of various kinds of real-world facilities or processes (Law and Kelton 1991)
Discrete-event simulation
Object oriented modelling
OOPs based simulator for modeling flexible supply chains
Need for Object Oriented Supply Chain Simulation
Supply chain flexibility offers many challenges and opportunities
It offers decision choices as the system evolves which is dynamic in nature
There is a need for developing a modeling environment to deal with flexibility and dynamic decision making
A OOPs based simulation system is developed and explored for its efficacy in this research
Advantages of Object Oriented Modeling
Inheritance
A class of objects can itself be linked to one or several super-classes from which it acquires characteristics and behavior
Encapsulation
Describes its characteristics along with its relationships to other components and the functionality of the object
Allows structured development of the model
Hides unimportant details
Modularity
Provides a very high degree of code reusability
Advantages of Object Oriented Modeling
Allows the model builder to develop the models with much less effort
Suitable for modeling distributed systems having client-server architecture
Plug-and-play software capability
Interoperability across the network
Platform independence
Allows complex systems to be constructed with minimum of redundant work
Advantages of Object Oriented Modeling
A logical choice for developing custom or dedicated simulation models
Sub-components may be prefabricated by some expert group for a specific need or application
Productivity of software development improves if code is reused, since the specific modules are already extensively tested by their developers
Advantages of Object Oriented Modeling
Provides a natural mapping paradigm which allows one-to-one mapping between objects in the system being modeled and their abstractions in the object model
Allows the developer to achieve a faster transition of the conceptual model into the software implementation
Object-oriented models generally have a cleaner structure than the event oriented ones
Overall Architecture
Basic building blocks are used to create some lower level complex objects
Lower level objects are then used to define the higher level objects
Level 1 objects are made up of basic building blocks
Basic building blocks are combined with the object(s) of level 1 to form level 2 objects
Object Oriented Modeling of Supply Chains
Supply chain decision making requires rapid and flexible modeling approach at various levels of detail
Object oriented modeling can be used for
Designing and implementing reusable classes for building models of supply chains
Creating a supply chain object library
Facilitates rapid model development
Aid in application of the modeling architecture to specific scenarios at various levels of abstraction
Object Oriented Features in Arena Simulation Environment
Offers model development in object oriented manner by means of objects called “modules”
Modules are essentially composed of other basic level modules
Once properly developed, these modules can be reused in other simulation models
However…
Limitations of Object Oriented Features in Arena
Modules can be run only on systems having ARENA
Version Conflicts
Not suitable for distributed computing
Cost of buying this simulation package
Additional cost of buying the customized module libraries
What is the solution then?
Generic Programming Languages
Not as easy as developing models using simulation packages
However,
It is more general and the SC flexibility related issues can be modeled in detail.
Availability of customized object libraries for a variety of applications can significantly reduce the time and effort involved in model building process
It offers platform independence to a large extent
IT tool used: VB.Net
Ease of designing the user interface
Now fully object-oriented
Provides a very high degree of platform independence
only for Windows based platforms however
Supply chain flexibility and dynamic decision making can be developed as a customized option.
Research Gaps
Need to develop simulation tools ideally suited for flexible supply chain simulation
Effective modeling of Supply Chain Flexibility
Web-based simulation environment
Demonstrate benefits of collaborative decision making
Non-deterministic and dynamic modeling
Analyzing the impact of different control decisions in an integrated manner
Distributed computing needs to be explored
Research Gaps
Need to study the impact of information sharing under different IT options
Supply Chain performance under different levels of Demand History, Service Level, Demand Variance needs to be studied
There is need for demonstrative models to illustrate the benefits of IT tools focused on modeling of the flexible supply chains.
Overview of the Research Work
Development of the IT tools for modeling Flexibility and Dynamic decision making
Manufacturing systems and supply chains were modelled in terms of five types of flows: information flow, decision flow, material flow, resource flow and money flow
Extended the Multiple Entity flow perspective proposed by Wadhwa & Rao (2003)
Development of demonstrative simulation models for illustrating supply chain performance improvement by the use of IT
Overview of the Research Work
Supply Chain performance improvement under flexibility and dynamic decision making. Focus on inventory management.
Comparison of Inventory Control Policies under Deterministic Variability
Effect of Demand History on Supply Chain Performance
Effect of Service Level on Supply Chain Performance
Effect of Demand Variance on Supply Chain Performance
Supply Chain Management Defined
SCM is “the integration of business processes from end-user through original suppliers that provides products, services, and information that add value for customers” (Lambert et. al. (1998)
Modeling Elementary Supply Chain Constructs
Classification of Objects
Multiple Entity Flow Perspective
Action Points as Processes in the System
Classification of Objects
Multiple Entity Flow Perspective
Action Points as Processes in the System
Hierarchy of Object Used in Supply Chain Modeling
Modeling of a Supply Chain Network
Modeling of Supply Chain Nodes
Modeling of Supply Chain Operations
Modeling the Manufacturing System
Levels of Abstraction for Supply Chain Modeling
Modeling of a Supply Chain Network
As a collection of supply chain nodes
Each node is a fully autonomous unit
Define relationships between each pair of nodes
Two types of relationships
Buyers (can select Sellers)
Sellers (can only be selected)
Constrained relationships
By the level of respective nodes
Integration of Supply Chain Nodes
Multiple Supply Chains in a Collection of Supply Chain Nodes
Modeling of Supply Chain Nodes
Two kinds of Nodes:
Manufacturing (Value-adding)
Non-Manufacturing ( store the material and supply it to other nodes )
Flows through each node:
Material flow
Information flow
Money flow
Flows Inside node
Resource Flow
Decision Flow
Modeling of Supply Chain Nodes
Five Processes
Plan, Source, Make, Deliver and Return
Return
Out of scope of this work
Store
Additional Process
A Manufacturing Node
A Non-manufacturing Node
Integration of Major Supply Chain Operations
Make
Manufacturing operations
Product quantity is decided by planning
Produces the goods according to the control policies determined by production planning
Routing
Scheduling
Source
Decides the sellers from whom to procure necessary goods
A sourcing policy is a decision rule that determines the best seller(s) out of a number of available sellers in accordance with some predefined criterion e.g. Maximum Inventory, Minimum Lead Time etc.
Deliver (Transportation)
Out of a number of transports one or more transports are selected based on some pre-defined transportation policy like
Maximum Speed
Minimum Cost
Maximum Capacity
Inventory Management
Concerned with maintenance of sufficient amount of inventory to fulfil demands
Whenever the inventory of any item falls below the critical levels, the inventory management sends the order(s) to procure the required material or product to planning operation
Planning subsequently decides either to make or buy the required product
Modeling the Manufacturing System
Can be modeled by combining two basic building blocks
Materials (Transformed or Consumed)
Resources (Negligible Transformation/Consumption)
One or more resource is used to perform some operation on the material (called process )
Each product requires some processes to be performed in a specific sequence
Two decisions are taken before each process
Resource selection
Material selection
Typical Material Processing in a Manufacturing System
Modeling Supply Chain Decisions
Source Selection Policies
Inventory Control Decisions
Transportation Decisions
Production Planning Decisions
Source Selection Policies
Classification (based on no. of sources)
Single Source
Multiple Source
Transport Based.
Source Selection Rules
Shortest distance
Minimum cost
Maximum inventory
Preference selection
Probability based selection (only for multiple source policies)
User defined selection (only for single source policies)
Source Selection Policies
Probability Based Source Selection
Multiple Source Selection
Inventory Control Decisions
Demand Flow
Order Q
Order Upto
(s, Q) Policy
(s, S) Policy
Updated (s, S) Policy
Days of Supply, Demand Based (DOS Demand)
Days of Supply, Forecast Based ( DOS Forecast)
Inventory Control Decisions
Updated (s, S) Policy
Updated (s, S) Policy
Reorder Level ( s ) is calculated as
Where
LT is the lead time of the selected source
σ is the estimate of standard deviation of the demand in previous n periods
Z is the standard normal variate corresponding to the desired service level
Special Cases
n -period moving average ( Z = 0 )
Demand Flow ( n = 1, Z = 0 )
DOS Demand
DOS Forecast
Transportation Decisions
Each transport uses some transportation mode e.g. rail , road , air , or water
Depending on the location, not all transports may be possible for a node pair
Alternative transports are selected based on which transport modes are available between a node pair
Transportation Decisions
Alternative transports differ according to their specific characteristics
Each transport has some properties like capacity speed, cost, etc
Transport selection rules
Maximum speed
Maximum volume capacity
Maximum weight capacity
Minimum cost
User defined transport selection
Transportation Selection Policies
More Classifications in Transports
The loading in the selected transport may again be of two types
Pooled (all the products shipped between a node-pair are sent through the same transport)
Non-pooled (different products are shipped through different transports)
Based on capacity utilization of transport
FTL (Full Truck Load)
LTL (Less than Truck Load)
Transport selection with pooled transports
Transport selection with non pooled transports
Production Planning Decisions
Routing
Concerned with selection of best possible resources out of a number of available resources
Scheduling
Decides the timing of each process or each job in the manufacturing system
Quantity to be produced is determined by the inventory policy
Production Planning Decisions
Options Available
Produce as directed by inventory policy
Produce short batches
Once the product is routed to a resource, it is added to the queue of the corresponding resource
Routing policy is used to select the next resource for the next process when current processing is over
Sequence of resource selection and allocation continues until all the processes on the job are completed
Production Planning Operation
Determining the Make Quantity
Resource Selection Policies
Modeling the Supply Chain Building Blocks
Consists of
Modeling the Manufacturing System
Modeling the Transports
Modeling the Player Role
Modeling the Supply Chain Node
Modeling Node Interactions
Different objects in the SC Network are linked with each other, they can be represented using the concepts of Relational Database Management System (RDBMS)
Modeling the Manufacturing System
Modeling the Transports
Modeling the Player Role
Modeling the Supply Chain Node
Performance Metrics
Inventory related
Minimum Inventory
Maximum Inventory
Total Inventory
Average Inventory
Standard Deviation of Inventory
Performance Metrics Used
Service related
Backorders
Stockouts
Fill Rate
Service Level
Demand related
Minimum Demand
Maximum Demand
Total Demand
Average Demand
Standard Deviation of Demand
Supply Chain Performance Under Deterministic Variability
Experimental Setup
Demand Impulses
Simulation Parameters
Balancing the Inventory Policies
Effect of Impulse Amplitude
Effect of Impulse Width
Effect of Step Width
Effect of Number of Impulses
Demand Impulses
Simulation Parameters Variable 1 1 1 Impulse Width 1 Variable 1 1 Number of Impulses 0 0 Variable 0 Balance Gap 0.9 and 1.9 0.9 and 1.9 0.9 and 1.9 Variable Impulse Amplitude 100 100 100 100 Mean Demand 2 2 2 2 Transportation Lead Time (Days) 2 2 2 2 Information Lead Time (Days) 90 90 90 90 Observation Period (Days) 20 20 20 20 Warmup Period (Days) 110 110 110 110 Run Length (Days) Step Width Number of Impulses Balance Gap Demand Amplitude Parameter
Balancing the Policies
Each policy was balanced so that all of them gave same results for the test demand under steady state condition
Demand Flow: The test demand was a constant demand of 100 units per week. To fulfill the current obligations, each node has to keep a minimum of 100 units. Each node has to keep an initial inventory equal to four weeks of demand. As a result, an initial inventory of 400 units was allocated to each node.
Order Q: In this policy, orders are placed even when no there is no demand. Therefore, inventory builds up for each node, until the actual demand is received. As a result, all nodes only need to keep an inventory equal to the value of demand per week (100 units).
Balancing the Policies
(s, Q) Policy: The initial inventories for each node were same as those for demand flow policy. A reorder point ( s ) of 400 and order quantity ( Q ) of 100 was set for this policy.
(s, S) Policy: Initial inventories were kept same as the demand flow policy. Both reorder point ( s ) and reorder level ( S ) were set to be 100 units.
Effect of Impulse Amplitude
Effect on Individual Supply Chain Nodes
Effect on Retailer
Effect on Wholesaler
Effect on Distributor
Effect on Manufacturer
Effect of each policy on the Supply Chain
Effect along the Supply Chain
Effect of Amplitude on Individual Supply Chain Nodes
Performance Metrics Used
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demands
Retailer’s Total Inventory
Retailer’s Std. Dev. of Inventory
Retailer’s Backorders
Retailer’s Stockouts
Wholesaler’s Total Inventory
Wholesaler’s Std. Dev. of Inventory
Wholesaler’s Backorders
Wholesaler’s Stockouts
Wholesaler’s Std. Dev. of Demand
Distributor’s Total Inventory
Distributor’s Std. Dev. of Inventory
Distributor’s Backorders
Distributor’s Stockouts
Distributor’s Std. Dev. of Demand
Manufacturer’s Total Inventory
Manufacturer’s Std. Dev. of Inventory
Manufacturer’s Backorders
Manufacturer’s Stockouts
Manufacturer’s Std. Dev. of Demand
Effect of Amplitude on Supply Chain as a Whole Demand Flow Policy Order Q Policy (s, S) Policy (s, Q) Policy
Demand Flow Policy
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
Order Q Policy
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
(s, S) Policy
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
(s, Q) Policy
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
Effect of Amplitude on the Supply Chain as a Whole
Type of Impulse
Positive Impulse (0.9)
Negative Impulse (-0.9)
Performance Metrics Used
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demands
Negative Impulse Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
Positive Impulse Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
Effect of Demand History on Supply Chain Performance
Experimental Setup
No Information Sharing
Effect on Individual Nodes
Effect on Whole Supply Chain and Effect along the Supply Chain
Partial Information Sharing
Full Information Sharing
Comparison of Information Sharing Levels
No Information Sharing
Effect on Individual Supply Chain Nodes Retailer Wholesaler Distributor Manufacturer
Retailer’s Total Inventory
Retailer’s Maximum Inventory
Retailer’s Std. Dev. of Inventory
Retailer’s Backorders
Retailer’s Stockouts
Wholesaler’s Total Inventory
Wholesaler’s Std. Dev. of Inventory
Wholesaler’s Backorders
Wholesaler’s Stockouts
Wholesaler’s Std. Dev. of Demand
Distributor’s Total Inventory
Distributor’s Std. Dev. of Inventory
Distributor’s Backorders
Distributor’s Stockouts
Distributor’s Std. Dev. of Demand
Manufacturer’s Total Inventory
Manufacturer’s Std. Dev. of Inventory
Manufacturer’s Backorders
Manufacturer’s Stockouts
Manufacturer’s Std. Dev. of Demand
Effect on Supply Chain and Effect Along the Supply Chain
Total Inventory
Std. Dev. of Inventory
Backorders
Stockouts
Std. Dev. of Demand
Organization of Thesis
Organization of Thesis
Organization of Thesis
Organization of Thesis
Organization of Thesis
Significant Contributions of the Research Work
Development of an object-oriented supply chain simulation environment
Role of IT based tools are developed and used to study IT facilitated information and decision flows in flexible supply chains is studied
Development of a framework that incorporates different IT facilitated control policies in SCs
Comparison for inventory policies under deterministic variability and information sharing
Analysis of Supply chain performance under different levels of demand information (IT focus)
Significant Contributions of the Research Work
Analysis of Supply chain performance under different of Service levels
Analysis of Supply chain performance under different levels of demand variance
Analysis of supply chain performance under different level of information sharing with
Different levels of demand history
Different service levels
Different demand variances
Limitations and Scope for Future Research
The modeling environment can be extended in more directions like
Closed loop supply chains by adding return process
Manufacturing operations can be extended to include different kinds of production facilities
….
Focus on Inventory management only…
List of Publications
Published/Accepted for Publication
Postponement strategies for re-engineering of automotive manufacturing: knowledge-management implications , International Journal of Advanced Manufacturing Technology, Article in Press, doi 10.1007/s00170-006-0679-z.
Hybrid Tabu-Sample Sort Simulated Annealing (SSA) with Fuzzy Logic Controller: CIM System Context , Studies in Informatics and Control, June 2006, Volume 15, Number 2.
Flexible Supply Chains: A Context for Decision Knowledge Sharing and Decision Delays , Global Journal of Flexible Systems Management, Volume 7 Numbers 3 & 4, July -Dec 2006 (Accepted for Publication).
Impact of Supply Chain Collaboration on Customer Service Level and Working Capital , Global Journal of Flexible Systems Management (Accepted for Publication).
List of Publications
Under Review
A multi-criteria customer allocation problem in supply chain environment: an artificial immune system with fuzzy logic controller based approach , International Journal of Computers Communication and Control.
Inventory performance of some supply chain inventory policies under impulse demands , International Journal of Production Research, Manuscript ID: TPRS-2007-IJPR-0111.
Communicated
An Object Oriented Framework for Modeling Control Policies in a Supply Chain , International Journal of Value Chain Management
List of Publications National / International Conferences
Web Based Virtual Supply Chain Modeling to Enhance Learning , The International Conference on e-Learning (ICEL 2006), University of Quebec in Montreal, Canada, June 22-23.
Supply Chain Modeling: The agent based Approach , 12th IFAC Symposium on Information Control Problems in Manufacturing (INCOM-2006), Saint-Etienne, France, May 17-19.
Object-Oriented Approach for Simulation of Supply Chain , International Congress on Logistics and SCM Systems (ICLS-2006), Kaohsiung, Taiwan, May 1-2.
Comparison of some Supply Chain Management Software Applications , National Conference on Advances in Mechanical Engineering (AIME-2006), January 20-21.
Response to Examiner’s Comments
Comments of Examiner 1
No Information Sharing: Is it best for individual wholesalers and retailers?
As we move higher in the supply chain, the demand variability increases because of the inventory policy used
It is not that no information sharing is good for individual wholesalers and retailers, information sharing is just less important for them.
Full Information Sharing: Is it best for the overall system?
Whether full information sharing is best for the system or not is dependent on the inventory policy used
The thesis aims to demonstrate that after some particular level of information sharing, the investment in IT may not be economically justified
Comments of Examiner 1
If answers to (1) and (2) above is yes, then explain why optimization on IS level (information sharing) is necessary? Why would an intermediate value (of IS) would be optimal? Whose objective have you considered? Individual wholesalers/retailers or the whole system? Or a combination of the two?
It is important to find the level and type of information sharing
On page xxvii: IT should be information technology
The required change has been made.
Uncertainty in supply chain is demand side and the lead time size. When you consider disturbances: you could have considered lead time disturbances.
We consider this as a future area of research
Comments of Examiner 1
Advanced IT means: continuous review policies (for inventory). What implications does it have for your thesis?
In a continuous review policy, the inventory position is continuously monitored
Review period is one day; all the policies in our research are the continuous review policies
For single node (such as wholesaler or retailer): given demand and lead time uncertainty: optimal policy for lot sizing can be devised. Then it could be used in your simulation.
Decentralized decision making is found to deteriorate the supply chain performance
The decisions of one node may indirectly affect the performance of other (interaction effects)
Comments of Examiner 1
A schematic diagram of supply chain (number of plants), distributor (numbers) and the wholesaler/retailers (numbers) considered in the thesis can be given.
A schematic diagram of the supply chain considered in this thesis is given on page 136. Description of the same is given in section 4.5
Main focus of thesis is determination of optimal levels of controllable factors such as … modifying the thesis title.
Motivation of this research is to bring the information technology (IT) as a performance improvement solution in the supply chain
Information sharing and IT are mutually complimentary
The research highlights where and how much information needs to be shared for the optimal performance
Factors beyond the control of decision makers (uncertainty) and factors under decision-makers’ control … readability of the thesis.
The required tables have been added in the Appendix A
Comments of Examiner 2
The current developed framework is limited to only two players, i.e. manufacturing and inventory … more than three players?
There are four players in the supply chain considered in this research: Retailer , Wholesaler , Distributor and Manufacturer
In addition to the inbuilt player roles like supplier, manufacturer, distributor, wholesaler and retailer, users can also define their own Player Roles .
Network manufacturing is a new arena for modern manufacturing environment. How could … contribution in this field?
For network manufacturing also, this framework can still handle the execution side
In network manufacturing, the manufacturing of the finished product takes place through a coordination of multiple autonomous players. Such a network will have most of the players as manufacturing type players.
This framework can be used where higher level modeling of the manufacturing system is sufficient
Comments of Examiner 2
In this research, “overall supply chain cost” has been used as the major criterion for the supply chain performance. In fact, there are many Key Performance Indicators (KPI) reported in the supply chain management research work, such as agilability, lead time, flexibility, expandability, trust, etc. How could you consider these issues into your research framework?
The research framework, in its present form, has only the KPIs which were required for this research work, i.e. those related to inventory management
Since the framework is based on object oriented methodology, multiple KPI libraries can be added to it as and when need arises
What are the major bottlenecks in the implementation of the developed framework in real-life industrial case?
The framework has been developed considering a very generic nature of the supply chain
Comments of Examiner 2
What are the major limitations of the developed framework in this thesis?
The return operation of a supply chain is not available in the framework.
In the future, some other major supply chain operations may be added in the framework.
The effectiveness of the simulation environment can be immensely improved by incorporating some optimization algorithms for simpler supply chain decisions and some meta-heuristics for complex problems.
Another important direction for future work is to provide animated simulation similar to that available in other simulation languages.
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